The present invention relates to magnetic materials, and more particularly to electronic components having magnetic cores.
Numerous modern-day electrical circuits utilize magnetic core components in accomplishing desired objectives. Audio and alternating current (AC) transformers and inductors typically consist of iron, powdered iron, or ferrite magnetic substrates. While the precise composition of such substrates varies with respect to design goals, common form structures take the shape of rods, toroids, or pots having a primary winding coil and a secondary winding coil integral thereto. The windings are often parallel with respect to generated magnetic fields and define permeability and the operating parameters of the device. Such structures are typically bulky and physical dimensions often define the minimum size requirement of associated devices or subsystems.
Recently, low-profile substrates have become more popularly known, often taking the form of a matrix device of numerous beads or a flattened monolithic substrate with vias or through holes for plated or hard wire windings. One example of such a device may be found in U.S. Pat. No. 4,665,357, issued to Mr. Edward Herbert and incorporated herein by reference. The initial use of low-profile perforated plates for magnetic substrates was hampered, in part, to inaccuracies in modeling the inductance of such devices. Conventional modeling approaches proved inaccurate in light of the non-conventional structure which included magnetic material in the winding window. Although numerous combinations of hole patterns, conductor paths, and core compositions were possible, empirical formulas have been devised and published addressing such modeling issues. One such publication is a paper entitled "Inductance Modeling For A Mode-2 Perforated-Plate Matrix Inductor/Transformer", by S. Kirli, K. D. T. Ngo, W. M. Polivka, and M. M. Walters, IEEE Annual Power Electronics Specialists Conference 1993, pages 1131-1136.
Simultaneous to the continued development of improved low-profile inductors and transformers, solenoid type variable inductors eliminating external magnets and associated circuitry of previous devices were also improved. A permeability function based upon an RF signal in a first winding, and a perpendicular control signal in a second winding has been disclosed as an improved variable solenoid inductor. To such end, application Ser. No. 08/169,083, having the same assignee as the present disclosure is directed to such improvements and is incorporated herein by reference.
Consequently, there exists a need for a low-profile inductor of high reliability, fast operating speed and low cost.